A shorthand format for an expression consisting of a concatenation of parts of variables.
LHS objects are used in flattening the module hierarchy. They are called LHS objects because they are also used to represent the left-hand sides of assignments.
An LHS object is simply a list of lhrange objects. The meaning of an LHS object is the concatenations of the bits of all of its lhrange objects, in the order given (LSBs-first).